Restricting Microsoft 365 Admin Roles with Entra Privileged Identity Management and Just-in-Time Access

Standing administrative privileges remain one of the most exploited weaknesses in cloud identity environments. When an account holds a permanent Global Administrator or Exchange Administrator role, that privilege is available to an attacker at any moment the credential is compromised, whether through phishing, token theft, or session hijacking. For organisations in WA Government and financial services, this standing exposure sits directly at odds with audit expectations for least-privilege administration.

The Essential Eight mitigation strategy for restricting administrative privileges calls for privileges to be validated, limited to the tasks required, and revoked when no longer needed. Microsoft Entra Privileged Identity Management (PIM) provides a native pattern for applying these principles to Microsoft 365, replacing permanent role assignments with time-bound, approved, and audited activation.

The problem with standing global admin rights

Persistent administrative roles create three distinct issues. First, they widen the attack surface continuously rather than only during genuine administrative work. Second, they make it difficult to demonstrate to an auditor who held which privilege at a given point in time. Third, they encourage role sprawl, where accounts accumulate high-privilege assignments that are rarely reviewed and seldom removed.

A least-privilege model addresses all three by making elevated access the exception rather than the default state. Administrators hold no active privilege until they need it, request it, and have that request approved.

How PIM enforces just-in-time activation

PIM introduces the concept of an eligible assignment. Rather than being permanently active in a role such as User Administrator or Security Administrator, an account is made eligible for it. The privilege remains dormant until the administrator activates it for a defined window, after which it lapses automatically.

Activation can be shaped by several controls that map cleanly to Essential Eight expectations:

• Time-bound access. Each activation is limited to a maximum duration, commonly a few hours, after which the role deactivates without manual intervention.
• Multi-factor authentication on activation. Administrators can be required to satisfy MFA at the moment of elevation, not only at initial sign-in.
• Justification and ticket references. Activation can require a business reason, creating a defensible record that ties privilege use to a specific task.
• Approval workflows. Sensitive roles can require a nominated approver to authorise each activation, separating the person requesting access from the person granting it.

This model means that even if an eligible account is compromised, the attacker inherits no active administrative privilege. They would additionally need to satisfy MFA, provide justification, and in many configurations wait for human approval.

Access reviews and periodic recertification

Time-bound activation controls day-to-day privilege use, but eligibility itself must also be governed. Access reviews allow an organisation to recertify who remains eligible for each privileged role on a recurring schedule. Reviewers confirm whether continued eligibility is justified, and assignments that are no longer required are removed.

For regulated organisations, this recurring recertification produces exactly the evidence auditors expect. It demonstrates that privileged access is not simply granted and forgotten, but is examined, attested, and pruned on a defined cadence.

A practical rollout approach

Adopting PIM is best treated as a staged programme rather than a single switch. A workable sequence is as follows:

• Inventory existing standing administrative assignments across Microsoft 365 and Entra to establish a baseline.
• Prioritise the highest-privilege roles, starting with Global Administrator, and convert permanent assignments to eligible ones.
• Define activation policies per role, setting maximum duration, MFA, justification, and approval requirements according to sensitivity.
• Maintain a small number of break-glass accounts that are excluded from conditional restrictions, stored securely and monitored, to prevent lockout.
• Configure recurring access reviews and integrate PIM audit logs into your security monitoring.

Break-glass planning deserves particular attention. Emergency access accounts should be excluded from policies that could prevent sign-in during an outage, held under strict physical and procedural control, and alerted on whenever used.

Demonstrating compliance

PIM produces detailed logs of eligibility changes, activations, approvals, and review outcomes. These records allow an organisation to answer the questions auditors most frequently ask about administrative privilege: who could act as an administrator, when they actually did, why, and who authorised it. Delivered through a Microsoft-native capability, this pattern gives WA Government and financial services organisations a concrete, defensible route to the least-privilege posture the Essential Eight requires.

References

• Microsoft Entra Privileged Identity Management documentation
• ACSC Essential Eight Maturity Model
• Microsoft Entra ID Governance licensing fundamentals